Natural Selection Flashcards
What are Darwin’s observations and deductions
- Species are reproduce: species are aware of springs produced are not all going to survive so by producing then someone still survive because of survival of the fittest.
- Population tend to remain fairly constant: since there is a struggle for survival individuals are eaten or die diseases so the population dies out.
- That is variation within a species: those with beneficial adaptations or characteristics that help them in their environment are more likely to survive and reproduce.
- Offsprings often resemble their parents - characteristics are inherited: those who survive and reproduce have the most beneficial characteristics to pass to the next generation.
What are Darwin’s deductions?
1) There is a struggle for survival. Individuals get eaten, die of disease or competition for resources.
2) individuals with characteristics that best adapt for their environment are more likely to survive and reproduce.
3) If these characteristics can be inherited, then the organism will pass them onto their offspring.
What is evidence for evolution?
1) fossil different species were alive in the past these have become extinct a new species have arisen.
2) fossil remains show species getting more and more complex as time goes on while retaining similarities. It also shows extinction and arrival of forms this evidence can be used to build phylogenetic trees.
What are problems with fossil records?
- there is suspected fake fossils
- fossils records tend to be incomplete
- usually only the hard parts of the animal fossil remain and many organisms do not have hard parts
- They are only formed in certain conditions
- can be destroyed by movement of rocks .
What is the most recent evidence for evolution?
- biological molecules: many biological molecules are found in all organisms suggesting that all species are raised from one common ancestor. Closely related to species have more similarities.
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protein variation: vital proteins such as DNA/RNA primaries are found in all living organisms. Higher organisms have added sub units that improve regulation.
-cytochrome c protein used in respiration shows pattern of changes. More change = more evolutionary distance. -
dna: sequencing the bases in DNA allows for comparison more differences found means that there is greater evolutionary distance
-mitochondria are passed offspring in the egg during sexual reproduction. mutations in the mitochondria are more common as mitochondrial DNA as less to checking occurs compared to genomic nuclear DNA
Variation can be used to trace human evolution
What is adaption?
Adaption is a feature that enhances survival and long-term reproductive success
What should a well adapted organism be able to do?
- find enough feed/photosynthesise at a fast enough rate
– find enough water plus mineral ions
– Defend itself from predators and diseases
– Survive the physical condition of its environment such as temperature, water availability and light intensity
– Respond to changes in its environment
– Be able to reproduce successfully
What is behaviour adaptation?
- This is when an aspect of a behaviour of the organism that allows it to survive where it lives
– Innate : inherited from genes
– Learned behaviour: learned from experience or observing other animals
What are examples of behavioural adaptations?
– Survival behaviours: animals play dead or a rabbit freezes in danger
– **Court ship: exhibit elaborate courtship behaviours to attract a male scorpions perform a dance
– Seasonal behaviours : help organisms in environment
Migration: move from one region to another them back if conditions are better
Hibernation : a period of inactivity
– Caterpillars are able to act like ant through sound and imitation so answer rescue it and take it back to the nurse and the caterpillar eats the baby ants
What is physiological adaptations?
- An internal and biochemical feature that assure the correct functioning of cell processes
What are examples of physiological adaptations??
– poison production: produce venom and plants produce poison
– Antibiotic production : bacteria produce antibiotic
– water holding: stool water in the body for long periods of time
– Mutations occur organisms are able to detect chemicals and poison
– Higher affinity for oxygen
What are Anatomical adaptation?
– Any structure that enhances the survival of the organisms
What are examples of anatomical adaptations?
– Teeth: shape and type of teeth are To its diet
– Camouflage : the colour of an animal blend into its environment making it hard to sport
– Body covering : hairs scales spines
– himiary : copy animals appearances or songs to allow a harvest pray to protect themselves from predators
- barnacles in a place where there isn’t much food have either wide opening to the shells shell and thick shells
What is convergent evolution?
Adaptations are controlled by the environment. This means that evolutionary distant species that live in similar habitats or exploit similar ecological niche of them evolve similar adaptations.
What is natural selection?
Genetic variation
Random mutations cause different alleles of genes
This causes intraspecific variation within a species.
Very occasionally new alleles may be beneficial
Selection pressure
Organisms have to compete for survival
Selection pressure are environmental factors that greater chances of survival for others, hence will production for some members of a proper and lower chances for others.
Selection pressure includes availability of suitable food, predators , diseases, physical or chemical factors and different habitats have different selection pressures .
Reproductive success
Organisms with advantageous adaptations are more likely to survive and reproduce.
They pass on all that code for beneficial characteristics to their offsprings
** repeated over many generations**
This process is repeated over many generations so the beneficial allele becomes more frequent in the population population therefore the proportion of the population possessing the advantages characteristic increases 
